Methods. Using the
hand-behind-the-neck and -back methods, we manually tested the
range of motion (ROM) of the shoulder joints of 91 uninjured
semi-professional rugby union players who consented to
participate in the study. Profiling and classification of
thoracic posture was performed according to the New York Posture
Test. Activation patterns of the upper and lower trapezius,
serratus anterior and infraspinatus scapular muscles were
determined by electromyography. The isokinetic muscle strength
of the rotator cuff muscles was determined at 60°/sec by
measuring the concentric and eccentric forces during internal
rotation (IR) and external rotation (ER).

Results. Participants presented with
non-ideal or unsatisfactory internal (59%) and external (85%)
rotators of the shoulder. A slightly abnormal or abnormal
forward head posture was observed in 55% of participants, while
68% had an abnormal shoulder position in the lateral view. The
muscle activation sequence of the rotator cuff muscles was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. The isokinetic
ER/IR muscle-strength ratio during concentric muscle contraction
was 64% (standard deviation (SD) ±14) for the left shoulder and
54% (SD ±10) for the right shoulder. The ER/IR ratio for
eccentric muscle contraction was 67% (SD ±12) and 61% (SD ±9)
for the left and right shoulders, respectively.

Conclusions. Non-ideal or
unsatisfactory flexibility of the external rotators of the
shoulder, a forward shoulder posture in the lateral view, and
weakness of the external rotators did not result in an abnormal
rotator cuff muscle activation pattern in this study. Postural
deviations may, however, increase the risk of shoulder injury in
rugby union players in the long term, and should be corrected.

S Afr J SM 2013;25(1):12-17.
DOI:10.7196/SAJSM.366

Poor posture, scapular dyskinesia, altered scapular muscle
recruitment patterns and shoulder-strength weaknesses or
imbalances may be associated with shoulder injuries in athletes;1 however,
this has not been proven conclusively for rugby players. Despite
the fact that rugby union enjoys increasing worldwide
popularity, it has one of the highest reported incidences of
injury.2
The shoulder is the second most common site of injury in the
rugby union player, accounting for almost 20% of injuries
related to the sport.3

Despite correlations between rounded
shoulders, severe kyphosis and forward head posture with
inter-scapula pain among the general population,4
similar findings are limited with regard to rugby union players.
There have been reports, however, of a relationship between
postural deviation and incorrect shoulder kinematics.5

Knowledge of the patterns of shoulder muscle
timing and the functional capabilities of the scapular rotators
is vitally important to understanding the behaviour of the joint
system, particularly under demanding circumstances such as
participation in sport.6,7
Scapulothoracic dysfunction is often seen in patients with
shoulder problems.1,8 Among
swimmers with shoulder injuries, there is significantly
increased variability in the timing of activation in the upper
and lower part of the trapezius muscle,1 reflecting
inconsistent or poorly co-ordinated muscle activation.1 With regard to rugby players, in a
study to define muscle-activation patterns in selected shoulder
girdle muscles during a front-on tackle in asymptomatic
subjects,9 a consistently earlier activation
of the serratus anterior muscle was observed prior to impact,
compared with the pectoralis major, biceps brachii, latissimus
dorsi and infraspinatus.9

A combination of electromyography (EMG) and
isokinetic dynamometry could provide information regarding the
function of shoulder musculature in sport.6]
It has been suggested that the functional strength of the
rotator cuff muscles and the rotator-strength ratio are
significant predictors of the likelihood of shoulder injury. The
unilateral muscle ratio – the antagonist/agonist muscle-strength
ratio of the infraspinatus and teres minor muscles v. the
subscapularis and supraspinatus muscles on the ipsilateral side
– is also believed to be important in isokinetic testing.10
A sufficient balance between agonist and antagonist muscle
groups apparently provides dynamic stabilisation to the shoulder
joint.10 To provide optimal muscle balance
and functional capability for overhead athletes, the strength of
the external rotators of the glenohumeral joint should be 65 -
75% of that of the internal rotator muscles.10
Muscle-strength ratios that lie outside the proposed normative
ranges may increase the risk of injury to athletes.11
Furthermore, there is evidence that rugby union players,
especially forwards, display poor antagonist/agonist
muscle-strength ratios with regard to their shoulder rotator
muscles.12

Previous research has indicated a
possible association between posture, isokinetic strength,
scapular muscle recruitment patterns and injury among the
general population and overhead athletes.1
However, there are few available profiles of rugby union
players with regard to the aforementioned factors and the
possible associations thereof with injury. The compilation of
such profiles for uninjured players could, in theory, assist
in the identification of rugby union players who are more
likely to be at risk of future injury to the shoulder area.
The aim of our study was, therefore, to profile rugby union
players accordingly, to assist in the identification of
possible musculoskeletal weaknesses.

Here we report on part of a larger study into
the occurrence of shoulder injuries during the 2010 rugby union
season at North-West University (NWU)-Puk Rugby Institute. The
shoulder is the most injured body region in backline players at
the institute. Previous work has
implicated certain biomechanical and postural aspects, such as
tight shoulder internal rotators and adductors, high body mass
and kyphosis, as possible intrinsic risk factors for these
shoulder injuries; however, the practical significance of these
correlations was limited by small sample sizes. We subsequently
performed a descriptive study to profile the thoracic posture,
scapular muscle activation patterns and rotator cuff muscle
isokinetic strength of right-hand-dominant semi-professional
rugby union players.

Methods

Participants

Ninety-five uninjured male rugby union players aged 17 - 31
years were recruited for the study. All participants were PUK
U19 A/B, PUK U21 A/B (NWU-Puk Rugby Institute) or Leopards Rugby
Union senior players (Provincial) based in the North West
Province. All participants gave informed consent to participate
in the study following an explanation of the test procedure and
study protocols. The Ethics Committee of NWU approved the study
(NWU-00048-11A1). All participants were tested in the pre-season
to ensure that they were uninjured during the test phase.
Left-hand-dominant participants (n=4)
were excluded from the analysis.

Measurements

Demographic
information

The stature of each participant was measured to the nearest 0.1
cm with a stadiometer (Seritex) using the stretch-stature
method. Body mass was measured to the nearest 0.1 kg with an
electronic weighing scale (Micro). Participants completed an
information sheet surveying age, position of play, dominant side
and previous injuries.

Shoulder range of motion

Biomechanical tests were performed according to a pro forma protocol compiled from
various sources. Shoulder range of motion (ROM) was determined
by the hand-behind-the-neck and -back tests.During both
tests, participants stood in an upright position. In the
hand-behind-the-neck test, participants were instructed to reach
over their ipsilateral shoulder with one hand and place it as
far down the spinal column as possible. The end-point of
movement was marked (representing the most inferior point) with
the shoulder in a position of external rotation (ER). Using the
same technique, the contra-lateral hand was placed as far down
the spinal column as possible, and the end-point was marked. The
distance between the two marks was measured. The players were
classified in terms of the discrepancies between the left- and
right-shoulder ROMs: a difference <1 cm was classified as
ideal, differences of 1 - 3 cm were classified as non-ideal, and
differences >3 cm were classified as unsatisfactory. During
the hand-behind-the-back test, the same principles were applied;
however, participants were instructed to place their hands as
high as possible on the spinal column (representing the most
superior point), with the shoulder in a position of internal
rotation (IR).

Thoracic posture

The New York Posture Test, designed for identifying 13
categories of deformities,13 was used for the evaluation
and identification of possible postural deformities in the
participants. Assessments were performed by capturing
high-quality digital photographs of the lateral and posterior
view of each participant. The camera was placed at a 90° angle
to the shoulders to ensure accurate calculation of angles. The
photographs were analysed with Dartfish software (version
4.06.0; DARTFISH, Switzerland). A score of 5 (normal posture), 3
(slightly abnormal posture/moderate deviation) or 1 (abnormal
posture/major deviation) was assigned to forward head, winged
scapulae/round shoulders and kyphosis aspects of the postures.
Uneven shoulders were measured by placing bright-yellow markers,
1 cm in diameter, on the posterior-lateral edges or acromial
angles of the left and right acromions. Uneven shoulders were
defined by the angle formed between the line connecting the
inferior edges of the markers and a true horizontal line. To
reduce the degree of subjectivity, New York Posture Test
criteria were used to score uneven shoulders as follows: 5 (0 -
2°); 3 (2.1 - 4.0°) and 1 (>4°).

Scapular muscle activation patterns

EMG activities of the scapulothoracic muscles were
registered by means of bilateral and simultaneous abduction of
both arms in the scapular plane (30° in front of the coronal
plane).1
The output of muscle activation was measured in microvolts
(mV). The firing sequence of the muscles was determined by
measuring latency times (ms). Consequently, the frequency
(percentage of times) that a specific muscle group fired in a
specific order was calculated. Accordingly, the muscles were
classified in terms of firing sequence. Data were obtained
with the Myotrace 400 Biofeedback system (Noraxon USA Inc.),
which operates by means of a 4-channel transmitter that allows
for simultaneous data collection from 4 strategically placed
electrodes. EMG electrodes were attached unilaterally to the
upper and lower trapezius, serratus anterior and infraspinatus
muscles, respectively, in accordance with Surface
ElectroMyoGraphy for the Non-Invasive Assessment of Muscles
(SENIAM) guidelines.14 The overlying skin on
the muscles was carefully prepared by abrading the outer
epidermal layer and removing oil and dirt with alcohol pads.
15
As only 4 channels were available to do the tests, the 4
muscles were measured unilaterally, after which the test was
repeated on the contra-lateral side. The participants started
the required movement with their arms resting next to their
sides. Bilateral arm abduction in the scapular plane was
performed to a point of 180° of abduction, after which
adduction was performed to the original starting point. The
test was standardised for both sides by regulating the tempo
of abduction and adduction. Participants performed the total
abduction-adduction sequence in 7 seconds. No resistance was
used or applied during the movement.

Rotator cuff isokinetic muscle
strength

The torque/peak power and muscle agonist/antagonist ratios of
the shoulder were tested with the Kin-Com 500H isokinetic
dynamometer (Chattanooga, Tennessee) with torque/power expressed
in Newton meters (Nm). Torque scores are representative of the
moment of force produced by muscle contraction for rotation
around a joint.12
During shoulder IR and ER, the participant was seated and
strapped to the seat. Testing was performed with the arms
positioned along the scapular plane, at 90° of abduction and
with 90° of elbow flexion. The contra-lateral arm was held
static against the chest throughout the test and the feet were
placed on a footrest. The shoulder axis of rotation was aligned
with the dynamometer’s axis of rotation. The 2 rotation points
were connected with an imaginary line that runs from the
dynamometer’s axis of rotation, through the humerus, towards the
acromion process. Each test started from the point of full ER.
Participants warmed up using the Monark 881E Rehab Trainer
(Monark, Sweden) for 3 min. Before the test commenced, each
participant was informed about the test procedure. Three
sub-maximal warm-up repetitions preceded the true test. Verbal
encouragement was given during the test to ensure maximal torque
output. The actual test consisted of a range of 6 concentric and
eccentric maximal contractions. The maximal concentric and
eccentric torque levels (in Nm) of the shoulder-girdle complex
were determined at speeds of 60°/sec for IR and ER. The
above-mentioned values were used to calculate the different
isokinetic ratios that were used to evaluate shoulder-muscle
performance: the antagonist/agonist ratio and bilateral strength
deficit ratio for concentric and eccentric contractions.
Furthermore, the functional strength ratio was expressed as the
eccentric ER torque production divided by the concentric IR
torque production of a shoulder. This functional ratio appears
to be relevant among overhead athletes, due to the fact that an
increased activity of the external rotators is required to
decelerate the humerus to centre the humeral head during a
ballistic action.16
The dominant and non-dominant shoulders of each participant were
measured.

Statistical analysis

SPSS software (version 17.0; IBM, New York) was used for
statistical analyses. Descriptive statistics were performed to
determine the characteristics of the participants as well as the
profiles of the different variables. Frequencies and means with
standard deviations (SDs) were calculated. Paired t-tests were performed to determine the
differences between the measurements of dominant and
non-dominant sides of the same individual. The level of
significance was set at p<0.05.

Results

Participant characteristics (Table 1) indicated that 42% played
rugby union as forwards. Statistically significant differences
were found between forwards and backline players with regard to
stature or height, weight, body mass index (BMI) and previous
injuries to the shoulder joint. Twenty-eight per cent of the
participants had suffered previous injuries to the shoulder,
including previous surgery, dislocations or subluxations, and
any injury that required the player to seek medical attention
for intervention. The injuries could have been sustained at any
stage, up until the end of the preceding season.

Table 1.
Participant characteristics

Mean (±SD)

Variable

All

(N=91)

Forwards

(N=40)

Backs

(N=51)

Age (years)

20.8 (±2.9)

20.8 (±2.7)

20.7 (±3.0)

Stature (cm)

182.0 (±8.1)

186.5 (±7.9)*

178.4 (±6.4)*

Mass (kg)

91.5 (±15.1)

103.3 (±13.3)*

82.2 (±8.6)*

Previous injury (%)

27.5

40

17.6

BMI (kg/m2)

27.5 (±3.3)

29.7 (±3.5)*

25.8 (±1.7)*

SD = standard
deviation; BMI = body mass index.

*Significant
difference (p<0.05).

ROM tests were performed to determine the comparative
flexibility of the shoulder internal and external rotators
(hand-behind-the-neck and -back tests, respectively) (Table 2).
Sixty-one per cent of the participants displayed non-ideal or
unsatisfactory flexibility of their internal rotators when
compared bilaterally. With regard to external rotator
flexibility, upon bilateral comparison 84% of the participants
were classified as non-ideal or unsatisfactory.

Table 2.
Frequency of shoulder flexibility (non-dominant v.
dominant)

ROM test

Ideal

%

Non-ideal

%

Unsatisfactory

%

Hand-behind-the-neck

39.3

42.7

18.0

Hand-behind-the-back

15.7

23.6

60.7

ROM = range of
motion.

From the New York Posture Test13 used to
evaluate thoracic posture (Fig. 1), more than half of the
participants displayed a slightly abnormal or abnormal forward
head position and a normal classification regarding a rounded
back. The majority of the participants displayed normal posture
with regard to uneven shoulders. Notably, 67% of the
participants were classified as slightly abnormal or abnormal
regarding their forward shoulder position.

Fig. 1. Thoracic postural profile of
participants according to the New York Posture Test.[20]

In terms of the average firing order of muscle
activation on the dominant side, the consensus sequence was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus and (iv) upper trapezius (Fig. 2; x-axis indicates the firing order, y-axis indicates the frequency of that
order). The serratus anterior had the highest frequency for
firing first (40%) and the lower trapezius had the highest
frequency for firing second (42%). A similar firing order was
observed on the non-dominant side, despite the fact that
different frequencies were observed (Fig. 3).

Fig. 2. Percentage of times that the
dominant upper trapezius, lower trapezius, infraspinatus and
serratus anterior muscles fired in a specific order during
abduction in the scapular plane.

Fig. 3. Percentage of times that the
non-dominant upper trapezius, lower trapezius, infraspinatus
and serratus anterior muscles fired in a specific order
during abduction in the scapular plane.

The results of testing the isokinetic shoulder
strengths with the dynamometer (Table 3) were that the
antagonist/agonist ratio regarding concentric shoulder rotation
of the non-dominant shoulder was slightly lower than what is
regarded as acceptable (64%). The corresponding ratio for the
dominant shoulder was even lower. A statistically significant
difference was observed between the values for the right and
left sides. A statistically significant difference was also
found between the antagonist/agonist ratio regarding eccentric
shoulder rotation of the non-dominant shoulder and the
antagonist/agonist ratio regarding eccentric shoulder rotation
of the dominant shoulder. The bilateral deficit during
concentric IR indicated that the participants’ non-dominant
shoulders were generally stronger than their dominant shoulders
during IR. With regard to concentric ER, the participants’
shoulders also appeared to be stronger on the non-dominant side.
The bilateral deficit during eccentric IR shows that this
right-dominant group was stronger on the dominant side. When one
considers the ER component, it seems that there is parity
between the average strength of the dominant and non-dominant
shoulders.

Discussion

The main objective of this study was to profile
semi-professional rugby union players in terms of thoracic
posture, scapular muscle activation patterns and rotator cuff
isokinetic muscle strength. The results indicated that the
majority of the players of the Leopards Rugby Union and NWU-Puk
Rugby Institute had less than ideal or unsatisfactory
flexibility of their external shoulder rotators when the left
and right shoulders were compared. Testing the flexibility of
the shoulder internal rotators indicated that only a small
percentage of the players had ideal flexibility when their left
and right shoulders were compared. This supports the findings of
a previous study17
of a diminished glenohumeral rotation range among professional
rugby players in comparison with a control group. Another study
also reported deficiencies in rugby players’ ROM, possibly
attributed to age, playing position, body mass index (BMI) or a
history of injury. It was previously found that age could be a
risk factor for decreased flexibility of shoulder rotators.17 This
could be related to the ageing of the glenohumeral soft tissue,
which may be accelerated by the training and injuries associated
with rugby.17
Deficiencies in ROM can be regarded as a risk factor for future
injuries.The
areas affected by decreased ROM are obviously less mobile.
Consequently, the joint’s supporting structures are dynamically
loaded and susceptible to intrinsic injury.

The results further indicate a higher
prevalence of abnormal thoracic posture than reported in the
literature for a non-sporting population. In the latter, 66% of
subjects had a forward head, 60% had thoracic spine kyphosis,
and 38% had rounded shoulders.2 This higher prevalence could
have been attributed to the poor flexibility of certain
anatomical structures, incorrect strength training, or incorrect
conditioning techniques applied among the players. To our
knowledge, no research has been done on incorrect training
techniques among rugby union players and the association thereof
with poor posture. However, it has been found that decreased
resting length of the pectoralis minor muscle could have a
negative influence on scapular kinematics. Therefore, a strength
programme where there is an imbalance between pectoralis major
strengthening (too much) v. latissimus dorsi strengthening
(insufficient), may contribute towards a shortened pectoralis
major muscle. This may also be exaggerated by insufficient
stretching of the pectoralis major muscle. This could result in
a scenario where posture, and consequently scapular kinematics,
may be negatively influenced, ultimately increasing the risk of
injury. However, there is an argument that certain postural
deviations such as abducted scapulae and rounded shoulder
posture may be advantageous for contact sport athletes.The theory
is that this posture allows the athlete to assume a tuck or
covered-up position quickly before making contact with defending
players. However, this seems to be a matter of opinion, and no
sufficient scientific data exist to confirm this theory. Some
believe that a link exists between posture and ROM. ROM loss may
be directly attributed to changes in thoracic posture. Such
changes may cause a reduction in the sub-acromial space, which
may cause impingement of supra-humeral soft tissue and
subsequently reduce the overall ROM and increase the likelihood
of injury. Theoretically, the high percentage of postural
deformities within this group, given the high physical demands
placed on rugby union players, could make this group susceptible
to future shoulder injury. Poor posture, therefore, not only
influences ROM but also impedes optimal scapular kinematics.

Knowledge of scapular muscle timing
patterns is vitally important in terms of our understanding of
the behaviour of the joint system, particularly under
demanding circumstances. It is relevant to profile rugby union
players with regard to these patterns. EMG analyses present
information on the sequence in which the scapular stabilisers
fire during shoulder movement along a scapular plane. In this
study the consensus sequence was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. Previous
research regarding EMG analysis of rugby players’
scapulothoracic muscles is limited, but the sequence of muscle
activation patterns in selected shoulder girdle muscles during
a front-on tackle in asymptomatic rugby players has previously
been investigated.5 The authors found a
consistently earlier activation of serratus anterior compared
with the pectoralis major, biceps brachii, latissimus dorsi
and infraspinatus. In accordance with our study, even though
different movements were measured, the results also indicated
that the serratus anterior was the first muscle to fire before
the other muscles tested. The influence of a superior labral
tear from anterior to posterior (SLAP lesion) on the onset of
EMG activity in shoulder muscles during a front-on tackle
among professional rugby union players has also been
investigated.18 Again, results
indicated that the onset of serratus anterior muscle activity
occurred significantly earlier than the other muscles
examined. This was seen, despite a trend towards a delay in
activation time of all the other muscles within the injured
group.19
It is obvious that serratus anterior plays a significant role
in the initial stabilisation of the scapulothoracic joint in a
simulated tackle situation. It is postulated that a delay in
the activity of serratus anterior, and the subsequent
impairment in scapular control, would allow the humeral head
to translate anteriorly and superiorly when the humerus
reached an abducted position in the tackle situation. This
could ultimately have a detrimental effect on the dynamic
stability of the glenohumeral joint. 19

During our study the most frequent firing
order for the trapezius muscles was the lower trapezius second
and the upper trapezius fourth. It has been postulated that an
early activation of the stabilising muscles at the proximal
scapulothoracic joint is important for maintaining proper
scapulothoracic stability throughout glenohumeral movement, and
that the correct sequence of these muscles’ activity is critical
for normal scapular kinematics.1 The muscles that aid the
serratus anterior in providing dynamic stability to the scapula,
provide a force by coupling around the scapula.8 The
infraspinatus plays a role in posterior glenohumeral joint
stability,but
its ability to provide early support to this joint is apparently
impaired by injury.It has been shown that the
infraspinatus activates significantly earlier than the
pectoralis major and latissimus dorsi during a simulated tackle
situation, but that this earlier activation is not seen among
injured players. This may be indicative of a failure of the
local control system that could possibly lead to increased
stress on the shoulder support structures.All the
muscles that were tested by means of EMG during this study have
important functions regarding the normal shoulder function of
rugby players, and it has been shown that the correct timing of
the activation of these muscles is significant.1,8,19 Altered
muscle activation patterns could contribute towards scapular
dyskinesia or indicate underlying injury, but normative data
regarding correct muscle activation patterns could possibly aid
in identifying potential weaknesses among scapular stabilisers
before injury occurs.

During this particular study, the
antagonist/agonist ratio regarding concentric isokinetic
shoulder rotation of the right shoulder was only 55%, while that
of the left shoulder was 64%. These findings are comparable with
those of another study17 where a concentric
external/internal rotator muscle ratio of 64% and 56% was
reported for rugby backline and forward players, respectively.
In both studies, the suggested antagonist/agonist
muscle-strength ratio of 65%16 was not found. This could
be relevant due to the fact that muscle imbalances around a
specific joint may increase the risk of injury to athletes.16 The
statistically significant difference between the players’
dominant and non-dominant antagonist/agonist ratios in the
current study is also noticeable. It is unclear why the dominant
shoulders generally tended to have weak antagonist/agonist
ratios. The tackle is the phase of play in which most game
injury events occur.20 If rugby players generally
tend to tackle with their dominant shoulder, the possibility
could exist that training and tackling over a period of time may
have a detrimental effect on the soft-tissue supporting
structures around the shoulder joint. This may impair normal
functioning and, even though players may not perceive being
injured, the wear and tear may be manifested in inadequate
shoulder-strength ratios. Another area of interest lies in the
fact that bilateral comparisons displayed that the participants
had, on average, stronger concentric IR and ER strength on the
non-dominant than the dominant side. Despite the fact that
varied results have been found regarding dominant v.
non-dominant shoulder strengths for overhead athletes, it has
generally been found that the dominant side is as strong as,21 or
stronger than,22
the non-dominant side. The findings of our study are therefore
contrary to those of previous research and may be indicative of
the weakness of our participants’ dominant concentric IR and ER
strength.

Study limitations

Certain limitations of our study should be acknowledged. We
employed the New York Posture Test due to a lack of objective
posture-measurement techniques; however, this test was initially
designed to classify adolescents and is therefore not ideal for
our group of participants, of whom a large proportion were
beyond the adolescent stage (range 17 - 31 years). Secondly,
regarding ROM measurement, a more scientific and objective
method is required than employed in this study. Lastly, with
regard to the measurement of scapular muscle activation
patterns, the information would be more relevant if the muscles
were to be tested during more functional, rugby-applicable
movements, such as tackling, for instance.

Conclusion

A large percentage of the participants in our study
displayed non-ideal or unsatisfactory flexibility of the
shoulder internal rotators. More than two-thirds displayed
forward shoulders and more than half of the participants had
unsatisfactory or non-ideal head positions. These are all
indicative of a kyphotic posture. The firing sequence in
abduction in a scapular plane and in both shoulders was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. As the
participants were uninjured, this firing order may indicate
the normal sequence of rugby players’ scapular stabilisers
during abduction in a scapular plane. It appears that the
firing order of serratus anterior, prior to those of the other
muscles studied, may be important for rugby players to
maintain healthy shoulder function. The isokinetic
shoulder-muscle strength and ratios indicated a possible
deficiency with regard to ER strength in the dominant
shoulder. This is possibly manifested in an unsatisfactory
antagonist/agonist shoulder rotation ratio. The profile of the
thoracic posture of the participants presents an image of a
kyphotic rugby player with an inappropriate ROM. This, in
combination with an apparent weakness of right shoulder
external rotator strength among the players, could have an
impact on the prevalence of future injury from a biomechanical
point of view, especially in the game of rugby with
ever-increasing physical demands placed on players. By
identifying these apparent musculoskeletal weaknesses, it may
be possible to rectify them pro-actively with prehabilitation.

Conflict of interest.
The authors have no
conflicts of interest to declare.

4. Griegel-Morris
P, Larson K, Mueller-Klaus K, Otis C. Incidence of common
postural abnormalities in the cervical, shoulder, and
thoracic regions and their associations with pain in two age
groups of healthy subjects. Phys Ther 1992;72(6):426-431.

4. Griegel-Morris
P, Larson K, Mueller-Klaus K, Otis C. Incidence of common
postural abnormalities in the cervical, shoulder, and
thoracic regions and their associations with pain in two age
groups of healthy subjects. Phys Ther 1992;72(6):426-431.